Lead Retention and Sealing Device

ABSTRACT

This application discusses, among other things, a header assembly for coupling a medical electrical lead to a medical stimulating device including a header having a capture mechanism within a bore of a lead retention device. In an example, when the lead retention device is retracted from the bore, the capture mechanism prevents the device from falling out. In another example, the header assembly has a vent disposed within the bore of the lead retention device that permits unrestricted flow of air when the lead retention device is retracted from an engagement surface.

CROSS REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly-assigned and co-pending application U.S.Ser. No. ______, Attorney Docket No. P0028700.00, filed Mar. 24, 2009,entitled “Full Visibility Lead Retention;” and U.S. Ser. No. ______,Attorney Docket No. P0026574.00, filed Mar. 24, 2009, entitled “SealingSetscrew,” all of which are herein incorporated by reference in theirentirety.

TECHNICAL FIELD

The present disclosure generally relates to implantable medical devices.More specifically and without limitation, this disclosure relates toheaders and setscrews for implantable medical devices. BACKGROUND

Many implantable medical devices such as pacemakers, defibrillators andneural stimulators deliver electrical therapy to tissue and sensevarious physiological parameters via medical leads. Such leads typicallyinclude an elongated flexible lead body with one or more electrodesdisposed at a distal end of the lead. The electrodes are connected to aterminal pin on the lead's proximal end by conductors that are disposedwithin the lead body.

The lead is typically coupled to a header of the implantable medicaldevice with a proximal portion of the lead being secured within theheader to prevent the lead from dislodging. In general, the header has aconnector block that includes a lead bore into which the lead's proximalportion is received. The connector block also includes a threadedsetscrew bore that intersects with the lead bore. The setscrew borereceives a setscrew that engages the lead to secure it within theheader.

The connector block is also coupled to a feedthrough pin, which passesthrough hermetic seals to connect with input and/or output nodes of theimplantable medical device's electronic circuitry. Typically, theconnector block is formed from a conductive material, such as metal,thereby permitting electrical connectivity between the lead and theelectronic circuit.

To provide a reliable connection of the lead within the connector block,the setscrew is typically comprised of metal. Thus, the contact with theelectrically active connector block causes the setscrew to beelectrically active. Exposure of the setscrew to adjacent body tissueand body fluids might result in undesired electrical conduction to theadjacent tissue. Additionally, because the setscrew bore intersects withthe terminal pin of the lead, ingress of fluid into the setscrew boremay result in the fluid contacting the terminal pin and this maycompromise the device's delivery of electrical therapy. Consequently, aseptum, typically referred to as a grommet, is disposed within thesetscrew bore to cover the setscrew, thereby sealing the setscrew boreand isolating the electrically active setscrew from body fluids. In oneexample, the grommet is a silicone disk that has an elastic quality andhas a slit that allows passage of a screw driver for tightening thesetscrew and re-seals upon removal of the torque wrench to block entryof body fluids. Additionally, when the shank of the setscrew isdisengaged from the threaded bore, the grommet retains the setscrew andprevents it from falling out.

While the use of a grommet has been satisfactory at preventing entry offluids into the device and contact between the electrically activesetscrew and surrounding tissue, it also substantially obstructs thevisibility of the lead's terminal pin within the connector block. Leadtip visibility is an indicator of full lead insertion into theconductive block. The visibility enables verification that a proper andsecure electrical and mechanical connection between the lead and theconductive block has been made.

BRIEF SUMMARY

Embodiments of the present disclosure provide, among other things, asetscrew that enables lead tip visibility as an indicator of full leadinsertion without requiring a grommet. In one embodiment, a setscrew isprovided having a metal core with an insulative coating disposed overthe core to electrically isolate it from body fluids and surroundingtissue without requiring a grommet. In one embodiment, the setscrewincorporates a sealing capability by including a sealing member that iscoupled to the setscrew. In another embodiment, the sealing member isdisposed within the setscrew bore to engage the setscrew. The sealingcapability seals the setscrew bore to prevent entry of body fluids intothe implantable medical device.

In one embodiment, the setscrew is provided with an engagement segmenton a head portion that is configured for engagement with a torquewrench. In another embodiment, a reinforcement sleeve is disposed on thesetscrew head. In one example, the reinforcement sleeve is disposed onthe entire head. In another example, the reinforcement sleeve isdisposed on the engagement segment of the head.

In another embodiment, an implantable medical device header has asetscrew bore configured for engagement with a setscrew. The setscrewbore is provided with an undercut that is formed at a location proximateto the exterior opening of the setscrew bore.

In another embodiment, the setscrew bore has a capture mechanism that atleast partially covers the exterior opening of the setscrew bore. Thus,when the setscrew is retracted from the threaded region of the bore, thecapture mechanism prevents the setscrew from falling out. In someembodiments, the capture mechanism has a radial opening having adiameter that is less than the diameter of the setscrew while stillallowing insertion of a torque inducing tool.

In another embodiment, an implantable medical device header is providedwith a lead bore and a setscrew bore with the setscrew bore having alongitudinal axis that extends in a transverse direction to, and incommunication with, the lead bore. In one example, the setscrew boreintersects with the lead bore at a location that is offset from thecentral longitudinal axis of the lead bore.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of particular embodiments of thepresent disclosure and therefore do not limit the scope of thedisclosure. The drawings (not to scale) are intended for use inconjunction with the explanations in the following detailed description,wherein similar elements are designated by identical reference numerals.Moreover, the specific location of the various features is merelyexemplary unless noted otherwise.

FIG. 1 is an illustration of an example implantable medical devicesystem that has a lead extending into a heart;

FIG. 2A shows a perspective view of a cut-out of the header of FIG. 1taken along lines 2-2;

FIG. 2B shows a perspective view of an alternative embodiment of theheader of FIG. 1 taken along lines 2-2;

FIG. 3 is a cross-sectional view of one embodiment of setscrew 200;

FIGS. 4A-C illustrate perspective views of the coupling between a torquewrench and a setscrew of the present disclosure;

FIG. 5 shows a cross sectional view of header 140 taken along lines 5-5(FIG. 1);

FIGS. 6A-B illustrate cross sectional views of header 140 in conjunctionwith a prior art setscrew;

FIG. 7 illustrates an alternative embodiment of a setscrew of thepresent disclosure;

FIG. 8 illustrates another alternative embodiment of a setscrew of thepresent disclosure;

FIG. 9A-B illustrate cross-sectional views of header 140 in conjunctionwith setscrew 200 of FIG. 8;

FIG. 10 illustrates a perspective view of yet another alternativeembodiment of a setscrew of the present disclosure;

FIG. 11 illustrates a perspective view of an alternative embodiment of acoupling of lead within a header;

FIGS. 12A-B illustrate alternative embodiments of a setscrew of thepresent disclosure;

FIG. 13 illustrates a perspective view of a first embodiment of a headerof the present disclosure;

FIG. 14 illustrates a cross-sectional view of the header of FIG. 13, inconjunction with a setscrew of the present disclosure;

FIG. 15 shows a cross-sectional view of the header of FIG. 14 inconnection with a lead;

FIGS. 16-17 illustrate an exemplary process for making the header ofFIG. 13;

FIG. 18A-B illustrate perspective views of a second embodiment of aheader of the present disclosure; and

FIG. 19 illustrates a perspective view of a third embodiment of a headerof the present disclosure.

DETAILED DESCRIPTION

The following description is exemplary in nature and is not intended tolimit the scope, applicability, or configuration of the presentdisclosure in any way. Rather, the description provides practicalillustrations for implementing exemplary embodiments of the presentdisclosure.

FIG. 1 is an illustration of an example implantable medical devicesystem 2 including an implantable medical device (IMD) lead 135connected to an IMD 10. In some embodiments, IMD 10 takes the form of acardiac pacemaker, defibrillator, neurostimulator, muscle stimulator, orgastric stimulator. As will be described in more detail below, theproximal end of lead 135 is coupled to a header 140 of IMD 10. Lead 135is secured in header 140 by a setscrew 200, which will be described inmore detail below. A distal end of lead 135 is coupled to an organ orany other desired tissue such as, for example, a heart 4. IMD 10delivers electrical stimulation to the tissue and/or detects electricalactivity via electrodes 136, 138. The illustration of the embodiment ofFIG. 1 showing IMD 10 coupled to a single lead 135 is merely for ease ofdescription of the various aspects of the present disclosure and is notintended to be limiting. For example, in one or more embodiments, IMD 10is coupled to a plurality of leads 135.

FIG. 2A is an isovolumetric sectional view of header 140 taken alonglines 2-2 (FIG. 1). Header 140 includes a connector block 150 comprisedof a suitable biocompatible material that is also electricallyconductive such as titanium. Connector block 150 includes a lead bore155 into which lead 135 is received. Connector block 150 also includes asetscrew bore 165 which receives setscrew 200. Setscrew bore 165 isoriented to be in alignment with, and intersect, lead bore 155. In otherwords, the central longitudinal axis of setscrew bore 165 is oriented ina transverse direction, relative to the longitudinal axis of lead bore155. Therefore, when setscrew 200 is threaded into setscrew bore 165, adistal tip 290 abuts lead 135 thereby securing it within header 140.

Setscrew 200 has a tool interface 300 that has a generally cross-shapedexternal drive interface. An external drive interface, generally, hasfaces that are aligned with the thread axis and face outward. Toolinterface 300 facilitates the threading of setscrew 200 into thesetscrew bore 165.

A sealing member 230 is coupled to setscrew 200. The engagement ofsealing member 230 between setscrew 200 and setscrew bore 165 seals theregion of header 140 extending inwardly of sealing member 230 to preventpenetration of body fluids. Sealing member 230 can be any component thatforms a fluid seal such as an o-ring or wiper seal. In some embodiments,the material used to form the seal is silicone.

FIG. 2B illustrates an alternative embodiment of the header 140 of FIG.2A incorporating sealing member 230 onto setscrew bore 165. Thus,sealing member 230 is circumferentially disposed within setscrew bore165. In some embodiments, engagement of setscrew 200 compresses sealingmember 230 against setscrew bore 165 or connector block 150 to form aseal.

FIG. 3 is a cross-sectional view of one embodiment of setscrew 200.Setscrew 200 includes a core 205 having a head portion 220 and athreaded shank portion 210. Shank 210 has a thread type compatible witha threaded setscrew bore 165 such, for example, as a standard 2-56UNC-2A screw thread. In one embodiment, core 205 also includes a neckedregion 235. Necked region 235 is formed between head portion 220 andshank 210 and has a narrower diameter than head 220. In someembodiments, the sealing member 230 is coupled to necked region 235.Core 205 includes a shoulder 280 disposed between necked region 235 andshank 210. Shoulder 280 is dimensioned to limit the downward movement ofsetscrew 200 by abutting connector block 150 (FIG. 2A). In theillustrative embodiment of FIG. 3, head portion 220 and shank 210 areintegrally formed to define unitary core 205. In some embodiments, core205 is comprised of a material having a high resiliency and strainendurance with the ability to be deformed under stress without cleavingsuch, for example, as a metal, organic metals or metallic polymers. Inother embodiments, the material is a suitable biocompatible material andor is electrically conductive such, for example, as gold, titanium ortheir alloys. In other embodiments, core 205 does not significantlydeform under typical loading conditions such as the forces exertedduring the assembly process.

Setscrew 200 includes insulating coating 225 that is disposed over aportion of core 205. In the illustrative embodiment, insulating coating225 is disposed over head 220 and necked region 235. Insulating coating225 will prevent exposure of surrounding tissue or fluids to electricalcurrent generated by IMD 10 (FIG. 1) and will prevent exposure of thelead 135 to the electrical signals of the tissue outside the header.Insulating coating 225 is generally a non-conductive material that hasdielectric properties. In one example, the material selected forinsulating coating 225 is a biocompatible dielectric material such aspolyaryletheretherketone (PEEK) thermoplastic, PARYLENE® polyxylylenepolymers, or a suitable polymer material. Insulating coating 225 iscoupled to core 205 by any conventional coating, molding or depositionprocesses. Insulating coating 225 is applied in a thickness to preventelectrical conduction via core 205 that may arise from contact with theelectrically active connector block 150. In an example where insulatingcoating 225 is primarily relied upon to provide electrical insulationfrom the surrounding medium, the thickness of insulating coating 225 istypically in the range of about 0.1 mm to about 0.8 mm (0.0039 inches to0.0315 inches). However, the thickness of insulative coating 225 mayalso be determined by the thickness necessary to ensure the force from awrench 302 (FIG. 4A) used to tighten and loosen the setscrew will notjeopardize the dielectric integrity of the insulator by tearing,cracking, penetrating, or otherwise weakening the insulative coating225.

FIGS. 4A-C illustrate the coupling between torque wrench 302 andsetscrew 200. As shown in the exemplary embodiment of FIG. 4A, toolinterface 300 is configured such that it interfaces with mating segment304 of torque wrench 302. The apex of tool interface 300 may beconfigured to be a guiding surface such that it facilitates thepositioning of torque wrench 302 over the setscrew 200. As an example,the apex of tool interface 300 is formed as a dome-shape. As illustratedin FIG. 4B mating segment 304 fits over tool interface 300, in directcontact with insulating coating 225. Thus, torque applied by torquewrench 302 is transferred to both insulating coating 225 and toolinterface 300. Due to insulating coating 225 being trapped betweentorque wrench 302 and core 205, the torque motion compresses insulatingcoating 225 against core 205. Accordingly, insulating coating 225 isplaced primarily under compressive stress, rather than shear stress. Theunderlying core 205 provides a high rigidity to insulating coating 225,which is placed primarily in compression, thereby increasing the torquebearing capability of setscrew 200.

FIG. 4C illustrates a cross sectional view of the coupling of setscrew200 to torque wrench 302. Prongs 306 of mating segment 304 fit inbetween the tool interface 300 walls. Thus, the torque motion exerted bywrench 302 places insulating coating 225 in compression against core205.

With reference to FIG. 5, a cross sectional view of header 140 takenalong lines 5-5 of FIG. 1 is illustrated. Lead 135 and setscrew 200 areinsertable into connector block 150 as described above. As the viewillustrates, lead 135 is engaged within connector block 150 therebyproviding the physical contact for electrical connectivity of lead 135with the electrical circuit (not shown) of IMD 10. The engagement oflead 135 with connector block 150 provides the electrical connectivitywith the electrical circuit. The overall diameter arising from theimplementation of setscrew 200 with a core 205 facilitates thevisibility of the engagement between lead 135 and connector block 150.Accordingly, the engagement of lead 135 with connector block 150 can beverified visually based on the protrusion of lead 135 from the connectorblock 150.

FIGS. 6A-B illustrate cross sectional views of assemblies of header 140with a prior art setscrew 100. FIG. 6A is a side cross sectional view(similar to lines 1-1 of FIG. 1) showing lead 135 and a prior artsetscrew 100, such as that disclosed in U.S. Pat. No. 4,316,471 issuedto Shipko et al., inserted into connector block 150. Setscrew 100includes a plastic head 120 that is coupled to a threaded metal shaftmember 110. Torque applied to head 120 is transferred to shaft member110 to threadedly engage setscrew 100 within header 140. The indirecttransfer of torque from a screwdriver (not shown) to shaft member 110,via head 120, places head 120 under sheer stress. Due to the sheerstress loading, head 120 is formed with a large diameter to preventtearing from the sheering stress. Thus, setscrew 100 has an overalldiameter that is much larger in comparison to setscrew 200 (FIG. 3).

FIG. 6B illustrates the top cross sectional view (similar to lines 2-2of FIG. 1) of setscrew 100 inserted into header 140. As illustrated, thelarge cross-sectional area of setscrew 100 obstructs visibility ofconnector block 150 and lead 135. As a result of the obstructedvisibility, setscrew 100 inhibits visual verification of the engagement,or lack of engagement, between lead 135 and connector block 150.Therefore, visual determination of whether lead 135 is fully engaged,partially engaged, or fully disengaged from connector block 150 isprevented.

Consequently, contrasting the assembly of FIG. 5 with the assembly inFIG. 6B, setscrew 200 facilitates visibility of the engagement betweenlead 135 and connector block 150. As described above, due to setscrew200 being formed with core 205 having both head portion 220 and shank210, the overall diameter of setscrew 200 is small, relative to setscrew100, while maintaining the same or better torque bearing ability.Moreover, while the overall volume of setscrew 200 is much smallercompared to that of setscrew 100, the engagement capability of setscrew200 is still sufficient to prevent dislodgment of lead 135.

Turning now to FIG. 7, an alternative embodiment of setscrew 200 havinga reinforcement sleeve 500 is illustrated. As described above,insulating coating 225 is contemplated to come in contact with torquewrench 302 during implantation. Depending on the thickness and/orproperties of insulating coating 225, or the amount of force exerted,the contact may result in chaffing, abrasion or other physical damagethat could potentially compromise the electrical insulation. Thus,reinforcement sleeve 500 is disposed over insulating coating 225 toprevent damage that may arise from improper contact between torquewrench 302 with insulating coating 225 or other mishandling of setscrew200. Reinforcement sleeve 500 is comprised of a resilient and highstrain endurance material, for example, a metal. In certain embodiments,the material is also a suitable biocompatible material, for example,gold, titanium or their alloys. In one example, the material forreinforcement sleeve 500 is an electrically insulative material thatprovides electrical isolation of setscrew 200. Reinforcement sleeve 500is coupled to setscrew 200 through any suitable bonding method such, forexample, as adhesion with an adhesive compound. In one embodiment,reinforcement sleeve 500 is bonded to head 220, over insulating coating225. While not intended to be limiting, the exemplary embodiment showsreinforcement sleeve 500 enveloping a portion of head 220.

FIG. 8 illustrates another embodiment of setscrew 200 of the presentdisclosure. In this embodiment, setscrew 200 has shank 210 detachedlycoupled to head 220. Head 220 includes an opening 605 that is disposedon distal end 600 into which a coupling segment 615 of shank 210 isreceived. In one example, opening 605 and coupling segment 615 areconfigured in an interlocking manner such as a lock and key arrangementsuch that coupling segment 615 is configured to fit into opening 605.

FIG. 9A-B illustrate cross-sectional views of header 140 in conjunctionwith setscrew 200 of FIG. 8. In the illustration of FIG. 9A, couplingsegment 615 (FIG. 8) is fully inserted within opening 605 (FIG. 8). Head220 is configured to be positioned at a stationary location withinsetscrew bore 165. As such, vertical motion of head 220 is inhibited butrotational motion is allowed. In this embodiment, when torque is appliedto setscrew 200, head 220 rotates about the stationary location and therotational movement causes vertical motion of shank 210 due to theengagement of the setscrew's threads with the connector block's threads.

As shown in FIG. 9B, rotation of head 220 causes shank 210 to beadvanced into setscrew bore 165 to abut lead 135. Alternatively, head220 can be rotated in the counter direction to retract shank 210 causingit to disengage lead 135.

FIG. 10 illustrates a perspective view of yet another embodiment ofsetscrew 200. In one example, shoulder 280 is tapered towards base 290of setscrew 200. The degree of taper of shoulder 280 is varied in therange between zero (0) to ninety (90) degrees. In another example,shoulder 280 has a rounded edge.

With particular attention now to FIG. 11, an alternative embodiment ofthe coupling of lead 135 within header 140 is illustrated. Setscrew bore165 is formed within connector block 150 in a substantially verticaldirection that is transverse to, and in communication with, thelongitudinal axis of lead bore 155. Lead bore 155 is formed in asubstantially horizontal direction, relative to the orientation ofsetscrew bore 165. However, unlike the embodiment of FIG. 2, the centrallongitudinal axis of setscrew bore 165 is offset from the midpoint ofthe longitudinal axis of lead bore 155. Thus setscrew 200 engages lead135 at a location other than tip 290. For example, in the embodiment ofFIG. 11, when setscrew 200 is threadedly coupled to the setscrew bore165, lead 135 is engaged by shoulder 280 of setscrew 200. In one or moreembodiments, the angle of the taper of shoulder 280 is preferablyselected such that the surface in contact between setscrew 200 with lead135 is approximately tangent to lead 135. Thus, in some examples, thetaper of shoulder 280 is selected to be about thirty (30), forty-five(45) or sixty (60) degrees. It will be appreciated that embodimentswhere shoulder 280 engages lead 135, the surface area in contact betweensetscrew 200 and lead 135 is greater than that of FIG. 2 where lead 135is engaged by base 290 of shank 210 of setscrew 200. Moreover, theoffset orientation described above permits setscrew 200 and lead 135 tooverlap, relative to one another, while still achieving the desired lead135 retention functionality.

With reference now to FIG. 12A, alternative embodiments of setscrew200A-B are illustrated. In the exemplary embodiment of setscrew 200A,head portion 220A of core 205 is shown having a star-shaped externaldrive configuration. The exemplary setscrew 200B shows head portion 220Bhaving a concave-shaped external drive configuration with the concaveregions having varying dimensions. It should be noted that theillustrative external drive configurations are merely exemplary and arenot intended to be limiting. In alternative embodiments, head portion220C has an internal drive interface as illustrated in the example ofFIG. 12B. Head portion 220C has a hollowed out region, configured withseveral lobed cutouts, that is integrally formed within head 220. Incomparison with an external drive interface, the internal driveinterface generally has faces aligned with the thread axis and that faceinward in relation to the contact surface of wrench 302.

FIGS. 13-15 illustrate magnified views of an exemplary embodiment ofsetscrew bore 165 of header 140. As earlier noted, IMD 10 is typicallyshipped with setscrew 200 already having been inserted in setscrew bore165. The diameter of setscrew bore 165 is typically sized to be slightlylarger than the external diameter of setscrew 200. Thus, theillustrative embodiments of header 140 prevent unintentional falling outof setscrew 200 from setscrew bore 165.

FIG. 13 shows setscrew bore 165 of header 140 having an undercut 700.Undercut 700 is formed within the setscrew bore 165. In someembodiments, undercut 700 is located proximate within the region betweenan exterior opening 170 and a midpoint of setscrew bore 165. Undercut700 extends circumferentially at least partially around setscrew bore165. The structure of undercut 700 resembles a furrow or a groove.Undercut 700 functions to receive a portion of setscrew 200 therebypreventing setscrew 200 from falling out of header 140. Additionally, aventing channel 710 that extends from the proximal opening 170 is formedwithin setscrew bore 165. In some embodiments, the longitudinaldimension of venting channel 710 is sized such that head 220 will belocated within a portion of venting channel 710 when setscrew 200 isdisengaged from setscrew bore 165. In one embodiment, venting channel710 is formed using molding techniques that incorporate venting channel710 in the formation of setscrew bore 165 within connector block 150. Inanother example, venting channel 710 is formed by any suitable processthat extracts the molding material, such as machining, or carving out toform the desired configuration, or depressing the wall of setscrew bore165 at the desired location during formation of header 140.

FIG. 14 illustrates a cross-sectional view of header 140 of FIG. 13, inconjunction with setscrew 200. In the illustrative embodiment, undercut700 receives a portion of setscrew 200 such, for example, as a regionhaving the largest diameter of setscrew 200 or a protrusion of theinsulating material. In the exemplary illustration, sealing member 230has the largest diameter of setscrew 200 and thus is received byundercut 700. Consequently, as setscrew 200 retracts from setscrew bore165, sealing member 230 is engaged within undercut 700 therebypreventing setscrew 200 from leaving the confines of setscrew bore 165.In alternative implementations, undercut 700 is formed of severalpartial regions spaced around setscrew bore 165.

Referring to FIG. 15, the insertion of lead 135 into header 140 of FIG.14 is illustrated. It should be noted that insertion of lead 135 intolead bore 155 will cause displacement of air within lead bore 155 andconnector block 150. With reference to FIG. 2 by way of illustration,when setscrew 200 is inserted into setscrew bore 165, sealing member 230compresses against the walls of setscrew bore 165 thereby sealing thebore 165 and preventing flow of air. Consequently, the air in lead bore155 causes a piston-like effect when lead 135 is inserted. In otherwords, the air will oppose insertion of lead 135 thereby encumbering theassembly during an implantation. Turning then to FIG. 15, as lead 135 isinserted into lead bore 155, the air within lead bore 155 is permittedto freely flow between venting channel 710 and sealing member 230. As anillustration, this free movement of air occurs through venting channel710. Additionally, the completed assembly of IMD 10 is typicallysterilized subsequent to insertion of setscrew 200. Venting channel 710also facilitates the sterilization process of header 140 since thesterilization fluid is permitted to flow through easily. Venting channel710 is located such that when setscrew 200 is fully unscrewed from theconnector block 150, fluids can freely pass through venting channel 710.Yet, when setscrew 200 is fully screwed into the connector block 150,fluids cannot freely pass by the sealing member 230 because the ventingchannel 710 does not pass through the zone between the location of thesealing member 230 when setscrew 200 is fully screwed into the connectorblock 150.

FIGS. 16-17 illustrate an exemplary process for manufacturing setscrewbore 165 having undercut 700 within header 140. It should be noted thatthe exemplary molding process for molding header 140 typically includesthe use of a mold 840 having identical features to those of the desiredheader 140 that are inverse to those of header 140. The manufacturingprocess used for the formation of header 140 is any suitable moldingprocess such, for example, as injection molding.

FIG. 16 is a perspective view of a portion of exemplary mold 840 for theformation of header 140. Mold 840 is provided with a setscrewbore-forming pin 800 for the formation of a setscrew bore 165. Setscrewbore-forming pin 800 has a raised rib 810 for the formation of undercut700. The diameter of raised rib 810 is sized to be larger than thediameter of the setscrew bore-forming pin 800 such that the point ofcontact between raised rib 810 defines the desired undercut 700. Pin 800is also provided with an extended longitudinal portion 805 for theformation of venting channel 710. At least one crest 815 is providedalong the circumference of a proximal end 870 of pin 800.

A molding process, such as injection molding, is performed to fill mold840 with a molding material that is shaped into header 140. The materialis allowed to cure and subsequently, the formed header 140 is separatedfrom mold 840. In one example, the step of curing includes providingsufficient time for the molded material to settle and cool to a roomtemperature, or about twenty degrees Celsius. The material used in themolding process is a creep recovering material, or has certaindeflection properties such that the material temporarily deforms whenstress is exerted upon it but substantially returns to its original formwhen the stress is withdrawn. In one example, the material is abiocompatible material that has elastic “memory” such as TECOTHANE®thermoplastic polyurethanes.

FIG. 17 illustrates the step of ejection of pin 800 during theseparation of mold 840 from the molded header 140. During the ejection,raised rib 810 causes an outward expulsion of the material proximate theraised rib 810. However, crest 815 will facilitate a controlled outwardexpulsion of the material at exterior opening 170 during the withdrawalmotion and prevent rupture. In one example, four crests 815 are providedso that the ejection of pin 800 will cause the material to be separatedinto quadrants during the expulsion. Subsequent to the ejection of pin800, the expelled material will substantially re-form back into itspre-expulsion location because of its elastic memory and deflectionproperties. This re-forming creates undercut 700 at the point of contactwith raised rib 810 and venting channel 710 at the location of extendedlongitudinal portion 805.

In alternative embodiments, a flattening process is additionallyutilized to further re-form molded header 140 and/or to create a smoothsurface finishing along exterior opening 170 of setscrew bore 165 andthe surrounding edge. In one example, the flattening process includes anannealing technique or application of heat to re-shape the materialaround exterior opening 170. In another example, the flattening processincludes the application of a physical force to depress the materialback into setscrew bore 165. In alternative embodiments, sealing member230 is coupled to setscrew bore 165. Sealing member 230 may be coupledusing any known bonding technique such, for example, as a siliconeadhesive.

FIGS. 18A-B illustrate an alternative embodiment of header 140 havingone or more protruding members 760. In the exemplary embodiment,protruding members 760 are posts molded as part of header 140 to extendadjacent to exterior opening 170. In an example, the protruding members760 are molded from the same material as the header 140. As illustratedin FIG. 18B, upon insertion of setscrew 200, the protruding members 760are reflowed downward toward setscrew bore 165 using any suitable reflowprocess such as ultrasonic welding so as to protrude over exterioropening 170 thereby preventing setscrew 200 from falling out.

FIG. 19 illustrates a capture mechanism 750 extending over exterioropening 170 of setscrew bore 165. In some embodiments, capture mechanism750 has a radial opening 755 having a diameter that is less than thediameter of setscrew 200. Thus, when setscrew 200 is retracted fromsetscrew bore 165, capture mechanism 750 prevents setscrew 200 fromfalling out of setscrew bore 165. In one embodiment, capture mechanism750 is a rigid thin plate that is formed such that it defines atrough-shaped opening 755. The exemplary opening 755 is sized to enableinsertion of torque wrench 302 for tightening or loosening setscrew 200.In one embodiment, channel 755 on capture mechanism 750 is aligned witha vertical axis of setscrew 200 to provide a continual line of vision tolead 135. Capture mechanism 750 is created from a bio-compatible rigidmaterial such, for example, as TECOTHANE® thermoplastic polyurethanes ortitanium. Capture mechanism 750 is bonded to header 140 proximate toexterior opening 170. In one example, capture mechanism 750 is bondedthrough the coupling of posts 760 to correspondingly sized holes 765 bya reflow process. In another embodiment, the capture mechanism 750 is aflat washer with a hole in approximately the middle that is large enoughto allow the torque wrench 302 to pass but smaller than the maximumdiameter of the setscrew to prevent the setscrew from falling out of thesealing bore. In one embodiment, capture mechanism 750 is formed as partof the header 140 by constructing a correspondingly shaped mold.

The specific shape and size of capture mechanism 750 is predicated onkeeping setscrew 200 from falling out while in its disengaged position.The shape and size of radial dimension 770 of opening 755 is controlledby various factors, for example, the assembly requirements including thesize and shape of the torque wrench 302, the shape of the tool interface300 and/or the coupling technique. By way of example which is notintended to be limiting, alternative embodiments of capture mechanism750 have radial dimension 770 formed to define a v-shape, or a u-shape.Additionally, the variation of radial dimension 770 facilitates thereduction of the spacing between multiple setscrew bores 165. Thus, thevariation of radial dimension 770 also enables reduction in size ofheader 140.

In the foregoing detailed description, the present disclosure has beendescribed in considerable detail in order to comply with the patentstatutes and to provide those skilled in the art with specificimplementations that facilitate the understanding of the novelprinciples of the disclosure. However, it is to be understood that theprinciples of the present disclosure can be carried out by specificallydifferent equipment and devices and that various modifications, both asto the equipment and operating procedures, can be accomplished withoutdeparting from the scope of the disclosure as set forth in the appendedclaims.

1. An implantable medical device (IMD) header assembly, comprising: aheader; a connector block disposed within the header, the connectorblock including a lead bore and a setscrew bore, the lead bore having atransverse orientation relative to and being in communication withsetscrew bore; and a capture mechanism disposed within the setscrewbore.
 2. The IMD header of claim 1, wherein the capture mechanismcomprises an undercut coupled proximate to an exterior opening of thesetscrew bore.
 3. The IMD header of claim 2, wherein the undercutextends at least partially within the circumference of the setscrewbore.
 4. The IMD header of claim 1, wherein the capture mechanismcomprises a protruding member disposed proximate to the exterior openingof the setscrew bore.
 5. The IMD header of claim 4, wherein theprotruding member is a reflowed post that partially covers the exterioropening of the setscrew bore.
 6. The IMD header of claim 4, wherein theprotruding member is a washer that partially covers the exterior openingof the setscrew bore.
 7. The IMD header of claim 2, further comprising asetscrew having: a head portion integrally formed with a shank portion,the head portion having an engagement segment configured for applicationof torque, wherein the shank portion has a threaded outer surfaceconfigured for coupling to a mating threaded bore of the IMD; a neckedregion disposed between the head portion and the shank portion; and aninsulating coating substantially encapsulating the head portion toelectrically isolate the head portion, wherein the insulating coating isplaced in substantial compression when the torque is applied to the headportion.
 8. The IMD header of claim 4, further comprising a setscrewhaving: a head portion integrally formed with a shank portion, the headportion having an engagement segment configured for engagement with atorque wrench, wherein the shank portion has a threaded outer surfaceconfigured for coupling to a mating threaded bore of the IMD; a neckedregion disposed between the head portion and the shank portion; and aninsulating coating substantially encapsulating the head portion toelectrically isolate the head portion, wherein the insulating coating isplaced in substantial compression when torque is applied to the headportion.
 9. The IMD header of claim 1, further comprising a sealingmember disposed within the setscrew bore.
 10. An implantable medicaldevice (IMD) header assembly, comprising: a header; a connector blockdisposed within the header, the connector block including a lead boreand a setscrew bore, the lead bore having a transverse orientationrelative to and being in communication with setscrew bore; and a ventchannel disposed within the setscrew bore.